Perl 6 Essentials

JayBonci writes "It may come as a surprise that within the pages of 'Perl 6 Essentials' lies what could be two books, despite its length. If not for lack of cover space, it could easily bear the names "Perl6 for Perl5 programmers" and "Parrot in a Nutshell". Both topics are concise and clearly covered, despite their relatively different audience." Read on for the rest of Jay's review. Perl 6 Essentials author Allison Randal, Dan Sugalski, and Leopold Totsch pages 208 publisher O'Reilly rating 9 reviewer Jay Bonci ISBN 0596004990 summary A solid look ahead at Perl 6, and a reference for Parrot developers

Make no mistake, Perl 6 isn't here yet, but it's coming. The book starts with a good explanation of "the plan"; chapters 1-3 deal with the history, goals, and design considerations of the project. It's a good conceptual overview of the process about how it has been run so far, and how it seems to be continuing. Chapter 3 is of special interest, as it showcases some of the in-depth thought that has been poured into the project. Though we all aren't language theorists, it helps allay some of the fears that change brings while being completely fascinating reading.

This first part of the book isn't very useful without a fairly solid Perl 5 background. It wastes no time in chapter 4 discussing syntactical differences in the v5 to v6 transition. Programmers should be pleased with the practicality of the approach to the new language, as it refers to the new structures and features, and how they solve simple workarounds that Perl veterans are used to in Perl 5. Currying, multimethods, class definitions and structures, new operator syntax, and the dynamics of the new regular expression engine (now called rules) are all touched on, and their values made obvious to the reader.

The last three chapters are for those interested in Parrot development and those who wish to port languages to Parrot. (There are active projects to port Python, Ruby, and even .NET to Parrot.) The section has a slight perl slant to it, but is really about the interpreter and compiling / running Parrot code. It is a fairly complete reference to the different parts of PASM (Parrot Assembly Language), and its role in porting languages to use Parrot. A comfort with assembly language basics is assumed in these sections, as the syntax and concepts of registers and machine code are made easier with general assembler familiarity. This part was somewhat dry for me, as it reads more like a reference than anything else, but it covers the topic fully without droning or leaving anything out. Examples are abundant and range from the simple, to the integrated, and are enough to get people started programming and writing tests with Parrot bytecode.

It should be noted that this book is valid and accurate now, but any development project can make changes quickly. There are places where the authors have admitted that a feature isn't in stone, and is possible to change. According to chromatic, an editor for O'Reilly, the plan is to update the book once a year until Perl 6 is released. Until then, a great place to keep up to date for the casual observer is at the p6p digest. This book goes down a lot easier than the Apocalypses, RFCs, and Exegeses, and I'd heavily suggest it to anyone who is serious about being ready for 6 or joining in on development . I preordered it from Amazon when I saw it was coming out, and am quite happy with my investment.

Table of Contents

1. Project Overview
   • The Birth of Perl 6
   • In the Beginning . . .
   • The Continuing Mission
2. Project Development
   • Language Development
   • Parrot Development
3. Design Philosophy
   • Linguistic and Cognitive Considerations
   • Architectural Considerations
4. Syntax
   • Variables
   • Operators
   • Control Structures
   • Subroutines
   • Classes and Objects
   • Grammars and Rules
5. Parrot Internals
   • Core Design Principles
   • Parrot's Architecture
   • The Interpreter
   • I/O, Events, Signals, and Threads
   • Objects
   • Advanced Features
   • Conclusion
6. Parrot Assembly Language
   • Getting Started
   • Basics
   • Working with PMCs
   • Flow Control
   • Stacks and Register Frames
   • Lexicals and Globals
   • Subroutines
   • Writing Tests
   • PASM Quick Reference
7. The Intermediate Code Compiler
   • Getting Started
   • Basics
   • Flow Control
   • Subroutines
   • IMCC Command-Line Options
   • IMCC Quick Reference

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Comments

I have reviewed this book for my site in the past.

[bethane]

Perl 6 Essentials is a sneak-preview of Perl 6, the widely-anticipated rewrite of the Perl programming language. Still in development, the Perl 6 project is a community-based effort to keep Perl vibrant well into the 21st century. This book covers the development not only of Perl 6 syntax but also Parrot, the language-independent interpreter developed as part of the Perl 6 design strategy. Although Perl remains a vibrant language with a fiercely loyal following, it has undergone many changes to keep up with new technologies and applications that were not anticipated when Perl was first introduced in 1987. Through its community-based development model, Perl has kept up with changing times and remained fresh when other languages might have stagnated. Internally, however, there have remained kinks and stumbling blocks that developers have needed to sidestep, long-abandoned features that have been maintained only for backwards compatibility, misdirected phrasings that have hindered more intuitive syntax structures, and a cacophony of modules that sometimes work well together, but occasionally don't. Perl continues to have a strong following devoted to its development, but in the meantime, a group of core Perl developers have begun working on Perl 6, a complete rewrite of the Perl language. While Perl's creative philosophy and common-sense syntax are sure to remain in Perl 6, everything else in the language is being re-examined and recreated. Perl 6 Essentials provides an overview of the current state of Perl 6 for those who await its release. Written by members of the Perl 6 core development team, the book offers an explanation of the various stages of the project, with reference material for programmers who are interested in what changes are planned or who may want to contribute to the project. The book will satisfy their curiosity and show how changes in the language will make it more powerful and easier to use. Perl 6 Essentials is the first book that offers a peek into the next major version of the Perl language. This book is essential reading for anyone interested in the future of Perl.

Perl 6 release date?

[dpuu]

According to chromatic, an editor for O'Reilly, the plan is to update the book once a year until Perl 6 is released

So, how many editions should we expect?

Back to the Future

[mbrod]

When I started using Perl 5 I figured it to be about 10 years ahead of its time. Being about 5 years since then I think I was pretty close to right.

Development of it is taking a long time but it has been worth it.

Some peoples minds don't seem to fit Perl 5 quite right and complain about it. Should have a lot more options of languages and style in P6.

Its a blazingly fast byte code interpreter. Having this Open Source is a very powerful thing and something many projects will find useful.

Parrot started out as a joke, and is still a joke

[Anonymous Coward]

If you've been keeping track of the Parrot project's progress for the past 2+ years you'd see that they're going nowhere fast. No language implemented other than a toy Basic language, no thread support, no object support, no exception support, no stable standard calling convention, no code module support (like Java .jar files), a proliferation of stupid one-off opcodes that should be method calls - and worse of all - no working Perl support. As for Ponie/Perl5 on Parrot - I'll believe it when I see it - this Parrot project blows more hot air than a thousands hair dryers. Tell you what - give me the $200,000 that they've been given and I will write the Perl6 interpreter for them. A lot of better open source projects have been written with little or no funding at all. There's no excuse for the pace of this project - it's directionless and leaderless.

Barely about Perl. Certainly not essential.

[Junks Jerzey]

This book isn't about Perl 6 at all, and there's nothing about it that's "essential." Part of the book is about the *plan* for Perl 6, but that's just plain silly. Who wants to read about the plan for some that's in the middle of development? Odds are that much of this part of the book will be completely invalidated long before Perl 6 is actually released.

The rest of the book--most of the book, actually--is about the Parrot virtual machine. Now, really, does this matter to Perl programmers at all? Is there a book about the innards of the interpreter used for Perl 5? Or a book about Python bytecode? It only matters if you're going to write a compiler that targets Parrot. And, again, note that Parrot is also a work in progress and will likely change dramatically before Perl 6 is actually released.

In short:
1. This is a book about vaporware.
2. Most of the book is not about Perl 6.3.
3. Why did O'Reilly even bother with this?

Mod parent up!

[quasi_steller]

Saying "you can do some really horrible stuff" in Perl in fact tells me that you probably don't know much about programming, at all. You can "do horrible stuff" in *any* programming language. Over the years I've seen more than my fair share of horrible C, C++, Java, Ruby, Python, Smalltalk, PHP, and yes, even Perl.

Absolutely true. People are always complaining that Perl alows a person to write obfucated code. What about C? The C programming language allows a person to write obfucated code as well. In fact it is so easy to write obfucated code in C that there is even a contest. But very few programmers would conclude that this makes C a bad language (although programmers might point to other aspects of C that might make it a bad language in their opinion). The C language is very powerfull, and part of this power is what allows a programmer to write obfucated code.

Re:The Superiority of PHP over Perl

[Bakaneko]

While I tend to prefer Perl as well, many of your reasons for prefering it are not entirely informed...

"* Perl is more standardized, due to it's greater history."

Not really sure of the point you're trying to make here. Niether project really has a standards body behind it. Perhaps you mean Perl is more accepted.
"* Perl has better DB support..."

Granted, although PHP provides a DB abstraction layer in Pear now, which all good PHP coders should be using...
"* Perl has structures..."

Some would say this is a bit ad-hominem, with the "not so in other (which?) languages part, but others would say the OO part is Perl's weakness. Either way, both languages (Perl in 5, PHP in 5) are working to improve their OO models.
"* Perl has better string manipulation"

True. Probably why PHP apes it in some respects.
"* PHP used Perl as part of it's basis"

This isn't really a good reason, since the obvious rejoinder is "ah, so PHP is an improvement on Perl then?". At any rate, its a bit silly to pick on another language for appropriating the good parts of other languages when you like Perl. Pot, this is Kettle, over, you are BLACK!

"PHP embeds..."

You mean, kind of like Mason with Perl? Really "violations of the OSI model" aside, this tends to be WHY PHP is so popular, because its very easy to use to do the odd simple thing because of this. Yes, you run into the problems with it when you start to do a larger project (which is why there are all those PHP template systems, I suppose.) but why deride something that works very well for the 80% of cases that are out there. It's also entirely possible to use PHP as a non-HTML-embedded language, of course.

That being said, I'd choose Perl in a heartbeat over PHP for a large project, particular one not Web related, for a number of reasons.

* Far better support for modules, and a much larger library of solutions already available.
* Some speed related issues out of the box.
* The afore mentioned string manipulation issues.
* Better ability to do things like signal handlers, and other "Unixy" things.
* What IMHO, I consider better language/character set support.

Re:Parrot started out as a joke, and is still a jo

[screenrc]

Is it not true that most Free Software projects
start small and then pickup exponentially? Debian
had less than 70 develpers for several years,
today there might be 1000 developers. Or, how
about testing the the 2.6 kernel? Most people
do not test the kernel until the release date
gets closer, at which point traffic and bugfixes
also increase exponenttially.